Before you plant any plantings around the yard it is important to prepare the landscaping bed for the plants that will be installed there.
First, all weeds and grass must be removed or killed in the bed. If you are mostly removing sod and there are no major weeds you can use a sod cutter or remove it by hand with a flat edged spade to the depth of an inch or so. You can also use a product like Roundup to kill the weeds and grass. After the plants start to die then remove the tops by mowing low and raking out dead foliage.
Cut a 4” edge on the outside of the bed to create a crisp bed line. If you are using edging of some kind this is a good time to install it.
If you need to amend the soil now would be a good time for that. Adding additional topsoil or a mixture of peat and sand and till it into the bed. Most soil will not need this step unless it is very poor. If you are planting groundcover however you should amend the soil by tilling in to a depth of 6” a combination of peat moss composted manure and sand equal parts to assure the groundcover establishes well.
Follow proper planting guidelines when planting your plants and if necessary amend the soil in the planting hole at this time.
After all the plantings are installed rake out the bed of all stones and dirt clods so the bed is ready for mulching.